1. Field of the Invention
The present invention relates to a vehicle-mounted image capturing apparatus that has multiple cameras installed on a vehicle to capture images, combines the images, and displays the resulting image. In particular, the present invention relates to a vehicle-mounted image capturing apparatus that facilitates viewing a border portion between the vehicle and its outside area.
2. Description of the Related Art
Japanese Unexamined Patent Application Publication Nos. 3-99952 and 8-305999 disclose vehicle-mounted image capturing apparatuses each having multiple cameras installed on a vehicle. Each of the cameras installed on the vehicle has a lens, such as a fisheye lens, that focuses light of an image of a wide-angle space area, and is adapted to allow the image focused thereby to be detected by a photodetector device, such as a CCD.
The vehicle-mounted image capturing apparatuses combine the images of areas outside the vehicle, the images being captured by the multiple cameras, so as to provide a projection image as viewed from above the vehicle and displays the projected combined image in combination with an image illustrating the vehicle. Such a display makes it easy to recognize the relationship between the vehicle and its surrounding area.
However, when a border portion between the vehicle and its outside area is to be photographed with the cameras provided at multiple locations on the vehicle and the resulting images are to be combined to provide a combined image, if the cameras are installed on door mirrors and so on at positions away from the vehicle, the border portion between the vehicle and its outside area can be almost correctly displayed using the combined image. However, cameras at a front end portion and a rear end portion of the vehicle are installed at positions slightly retracted from the front end portion and the rear end portion of the vehicle. Thus, part of a front area and a rear area of the vehicle surroundings is hidden from the cameras by part of the vehicle. Thus, even if the image captured by the camera is combined with other images, it is impossible to capture an image of an area adjacent to the front end portion or the rear end portion of the vehicle.
According to processing performed by a vehicle-mounted image capturing apparatus disclosed in Japanese Patent Application No. 3300334, for example, areas outside and adjacent to the vehicle whose image cannot be captured is regarded as a blind area or a precaution area and is filled with a certain color.
In such a known technique in which the combined image of surrounding areas outside the vehicle and an illustration image of the vehicle are combined, only the border line between the combined image and the illustration image, i.e., the border line indicating an outer edge portion of the vehicle, is displayed. Thus, it is difficult for an operator who views a display screen to recognize the actual vehicle border portion, making him/her feel unsure about the distance between the actual vehicle outer edge portion and an obstacle. Also, with the technique in which a vehicle illustration image is displayed on the display screen, the operator cannot check, for example, the steering angle of the front wheels by using the image.
When the blind area or the precaution area is filled with a specific color, as disclosed in Japanese Patent Application No. 3300334, the operator who views the display screen cannot intuitively recognize what the color-filled portion represents, i.e., whether the portion represents part of the vehicle or the ground, and thus cannot recognize the position of the outer edge portion of the vehicle.